LOCATION WHITEWRIGHT TXEstablished Series
TAXONOMIC CLASS: Loamy, carbonatic, thermic, shallow Typic Haplustepts
TYPICAL PEDON: Whitewright silty clay loam--pasture.
(Colors are for dry soil unless otherwise stated.)
A--0 to 5 inches; light brownish gray (10YR 6/2) silty clay loam, grayish brown (10YR 5/2) moist; moderate medium subangular blocky and granular structure; hard, friable; common medium and fine roots; few fine and medium pores; common wormcasts; few fragments of weakly cemented chalk that are 2 mm to 10 mm in size; few strongly cemented fragments of calcite that are 5 to 15 mm across the long axis; calcium carbonate equivalent is about 60 percent; calcareous, moderately alkaline; clear smooth boundary. (6 to 14 inches thick)
Bk--5 to 16 inches; very pale brown (10YR 7/3) silty clay loam,
pale brown (10YR 6/3) moist; few medium distinct brownish yellow (10YR 6/6) mottles; moderate fine and medium subangular blocky structure; hard, friable; common fine and medium roots; few fine pores; common wormcasts; about 20 percent by volume of weakly cemented platy fragments of chalk 5 to 20 mm across the long axis; most of the chalk fragments disintegrate upon moistening and gentle rubbing; few fine shell fragments; calcium carbonate equivalent is about 65 percent; few films and threads of calcium carbonate; calcareous, moderately alkaline; abrupt wavy boundary. (6 to 14 inches thick)
Cr--16 to 34 inches; white (10YR 8/1) weakly cemented fractured chalk, interbedded with thin horizontal strata of olive yellow (2.5Y 6/6) silty clay loam; cleavage planes of rock structure are evident in the chalk; the chalk becomes less fractured and more massive below 30 inches depth; few fine roots in the upper part in vertical crevices and between horizontal plates; calcareous, moderately alkaline.
TYPE LOCATION: Grayson County, Texas; from the intersection of Texas Highway 5 and Farm Road 121 in Van Alstyne, Texas, 0.75 mile east on Farm Road 121; 1.25 miles north on an unpaved county road; 100 feet west of road in pasture.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 10 to 20 inches. Siliate clay ranges from 20 to 35 percent in the control section. The soil is calcareous and ranges from 40 to more than 80 percent calcium carbonate equivalent.
The A horizon has colors in hues of 10YR, value 4 to 6, and chroma of 2 to 4. Where the horizon has moist values and chromas of 3 or less, it is less than 7 inches thick. It is silty clay loam or clay loam. Fragments of weakly cemented chalk range from none to about 15 percent by volume. They are platy and range from 2 mm to 3 cm across the long axis. The fragments are weakly to strongly cemented when dry but most of the fragments slake or soften on soaking in water.
The Bw horizon has colors with hue of 10YR, value of 5 to 7, and chroma of 2 to 4. Some pedons have mottles of brown or yellow that are believed to be inherited from the parent material. It is silty clay loam, or clay loam, or their gravelly counterparts. Fragments of weakly to strongly cemented chalk range from a few to 35 percent by volume. However, upon soaking in water, the chalk fragments slake to where the percentage of strongly cemented fragments range from a few to about 20 percent by volume.
The Cr horizon has colors in shades of gray, brown or white. It is weakly cemented platy chalk interbedded with thin strata of light yellowish brown, pale yellow, brownish yellow, or olive yellow clay loam or silty clay loam. The platy fragments of chalk are weakly to strongly cemented but can be readily cut with a spade
when moist. In most pedons the chalk becomes less fractured and
more massive at 25 to 40 inches depth.
COMPETING SERIES: There are no other series in this family, similar families include the Altoga, Brackett, Cuthand, Dugout, Eddy, Howe, Seawillow, Shiner, Stephen, and Quinlan series. Altoga, Cuthand, Howe, and Seawillow soils have sola more than 20 inches thick. Brackett, Dugout, and Quinlan soils are dry in the moisture control section for longer periods of time. In addition, Brackett soils contain fragments of hard limestone, Dugout soils have a lithic contact to limestone and Quinlan soils have mixed mineralogy and B horizons with redder hues. Eddy soils lack B horizons and have more than 35 percent chalk fragments in the control section. Shiner soils have a mean annual soil temperature of more than 72 degrees F. Stephen soils have mollic epipedons and mixed mineralogy.
GEOGRAPHIC SETTING: Whitewright soils occupy gently sloping to moderately steep uplands. Slopes are mainly 4 to 10 percent but range from 1 to 15 percent. The soil formed in chalk and interbedded marl of the Austin Group of Upper Cretaceous Age. The mean annual temperature is 63 degrees to 66 degrees F. Average annual precipitation ranges from about 35 to 41 inches, and the Thornthwaite P-E index ranges from 56 to 66.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Eddy, Howe, and Stephen series as well as the Austin series. Eddy and Howe soils occupy similar positions. Stephen and Austin soils occupy slightly higher less sloping positions. Stephen and Austin soils have mollic epipedons, and in addition, Austin soils have sola thicker than 20 inches.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for pasture. A few areas are planted to small grain and sorghum. Dominant pasture grasses are King Ranch bluestem, common and improved bermudagrass. Areas that were formerly in cropland are growing silver bluestem, sideoats grama, hairy grama, little bluestem, threeawn, and annual weeds. Woody vegetation is mainly scattered elm, hackberry, and small oak trees.
DISTRIBUTION AND EXTENT: North-central Texas; in the Blackland Prairie Land Resource area. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Grayson County, Texas; 1977.
REMARKS: These soils were formerly as a shallow phase of the Austin series and in more recent years they were included in the Brackett series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - 0 to 5 inches, the A horizon.
Calcic horizon - 5 to 16 inches, the Bk horizon.
Paralithic contact of chalk at a depth of 16 inches.